Perylene bisimides with rigid 2,2′-biphenoxy bridges

Abstract

The present invention relates to perylene bisimides with rigid 2,2′-biphenoxy bridges which are useful in a wide variety of applications and to novel to perylene bisimides with rigid 2,2′-biphenoxy bridges. The present invention also relates to the use of said compound(s) in color converters for improving the luminous efficacy of LEDs, to color converters and their use and to lighting devices comprising at least one LED or OLED and at least one color converter. The present invention also relates to a printing ink formulation for security printing comprising at least one perylene bisimide with rigid 2,2′-biphenoxy bridges and security documents.

Description

FIELD OF THE INVENTION[0001]The present invention relates to perylene bisimides with rigid 2,2′-biphenoxy bridges which are useful in a wide variety of applications and to novel to perylene bisimides with rigid 2,2′-biphenoxy bridges. In particular, the present invention relates to the use of said compound(s) in color converters for improving the luminous efficacy of LEDs, to color converters and their use and to lighting devices comprising at least one LED or OLED and at least one color converter. The present invention also relates to a printing ink formulation for security printing comprising at least one perylene bisimide with rigid 2,2′-biphenoxy bridges and to security documents.[0002]LEDs (light-emitting diodes, LEDs) and OLEDs (organic light-emitting diodes, OLEDs) are an important class of devices that convert electric energy into light. In particular, LEDs are attractive candidates to replace conventional light sources such as incandescent lamps and fluorescent lamps, since...

AI Technical Summary

Benefits of technology

[0838]Table III shows that a mixture of the orange-red fluorescent dye 2 of example 1 according to the invention, the prior art red fluorescent dye 3 and the prior art yellow fluorescent dye allow to make converters having a good average color rendering index, a good R9 value as well as a high photopic luminous conversion efficacy. It is evident that the admixture of the inventive dye improves the overall property profile of converters.

Problems solved by technology

Organic luminophore materials are not suitable, because the polymeric material and the radiation conversion luminophore are subject to relatively high thermal stress and radiation stress.

Because of the different brightnesses and operating conditions for the various light-emitting diodes (each LED is driven by a separate circuit), the multi-LED is technically complex and therefore expensive.

Moreover, component miniaturization of the multi-LED is severely limited.

However, a standard Ce:YAG-based white LED has high color temperatures (typically above 6000 K) and only emits cool-white light, because the red component in the spectrum is too weak.

Thus, the emission of the inorganic phosphors typically does not cover uniformly the visible spectral range, which reduces the possibility of mimicking the emission spectrum of sunlight or incandescent sources and, consequently, the color rendering performance of the lighting device is not satisfactory.

When only the yellow fluorescent dye is used, a low color temperature (warm white light) with a high color rendering cannot be achieved.

However, rare-earth elements are expensive and dangerous to health.

While organic red-fluorescent dyes with emission in the near infrared (NIR) region of the electromagnetic spectrum (also called IR-A, wavelength range from ca 700 nm-1400 nm) regions are known, a large number of them suffer from degradation and thus show an efficacy loss over the operational lifetime.

Degradation may be due to low photostability, low thermal stability and / or high sensitivity to moisture and oxygen.

A special disadvantage with red-fluorescent dyes is that part of their fluorescence band(s) often lies in the NIR region and thus is not perceived by the human eye due to reduced sensitivity of human eye to red wavelength.

Therefore, white LEDs are often not satisfactory in terms of their luminous efficacy.

Warm-white LEDs are inherently less efficient than cool-white LEDs, due to (some small) losses in the color conversion process and the broadband emission of red phosphors that extend into the near-infrared.

On the other hand, white LEDs having a high luminous efficacy are often inadequate in terms of color rendering index (CRI).

If the color rendering is poor, the light source will not be useful for general lighting.

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